Double pulse oscillator



Lm 1s, 1946. H. LIFSCHUTZ "2,402,169

DOUBLE PULSE OSCILLATOR Hard Lifffscvutz June 18, 1946. H. LlFscHu-rzDOUBLE-PULSE OSCILLATOR Filed March 27, 1942 2 Sheets-Sheet 2 wmdw im...lo vm m L* d l 0 W H Fatenie June I18, 1946l DOUBLE PULSE O SCILLATORu Harold Llfschutz, Washington, D. C., now by' judicial change of nameHarold Lyons Application March 27, 1942, serial No. 436,469 1s claims.(ci. 315-26) (Granted under the act o! March 3, 1883, as amended April30, 1928; 370 0. G. 757) This invention relates to oscillator circuitsand more particularly to circuits for generating double pulses.

There has been a need in the art for a circuit capable of generating adouble pulse output, since such output may beemployed in numerousinstances for controlling operation of or calibrating various electricalmachines. For example, the output of a double pulse generator may beutilized to measure the resolving time of an electronic counter circuit.or may be employed to operate electronic switches of the scale-of-twotype in which case the time that the switch is opened or closed isdependent upon the time interval of separation of the double pulses.l Y

It is therefore an object of the present invention to provide anoscillator circuit for generating double pulses.

Another object is to provide a double pulse generator which includesmeans for varying the time interval or the separation between the doublepulses.

Another object is to provide a double pulse generator with means formaintaining the time interval between the double pulses constant, and

including means to vary the rate of repetition of double pulses.

Another object is to provide a double pulse generatpr which includes apair of non-oscillating vacuum tubes each driven by a source of sawtoothvoltage whereby each of the tubes produce a pulse upon application ofeach cycle of a sawtooth voltage thereto, with means varying the timethat each of said tubes produce a pulse.

Stili another object of the invention is to provide a double pulsegenerator interconnected with an oscillograph in such a manner toindicate the double pulses whereby the time interval or separationtherebetween may be accurately measured.

Still another object is to provide a double pulse generatorinterconnected with an oscillosraph for indicating the output of thegenerator, with means synchronizing the output of the generator with theoperation of the oscillograph with a erence for the latter purpose beinghad to the appended claims. l

` In the drawings, wherein, similar referencia characters denote similarparts throughout the several views:

Fig. 1 is a block diagram of a double pulse generator interconnectedwith an oscillograph;

Fig. 2 is a circuit diagram of the generator disclosed in Fig. l; i

Fig. 3 is a schematic showing of the voltage applied 'to grid 36 of tubeshown in Fig. 2;

Fig.. 4 is a schematic showing ofthe voltages of grid 3l of tube 39shown in Fig. 2, and a Fig. 5 is a diagrammatic showing of the doublepulse output oi the oscillator disclosed in Fig's. 1 and 2.

With reference more particularly to Fig. 1 -of` the drawings a-doublepulsegenerator is'disclosed therein including a saw-toothwave generatorIIJ which simultaneously feeds saw-toothwave forms, through buierampliers Il and I2 to pulser circuits I3 and I4. The saw-tooth waveinput to pulser circuits I3 and I4 controls operation of the lattercircuits in such a manner that a negative and a positive pulse isgenerated at the output of ea'ch of the circuits upon application ofeach cyclev of the saw-tooth voltage Y thereto.- The pulsating outputsof pulser circuits timing wave for calibrating the double pulse patltern on the oscillosraph.

signed for purposes of illustration only and not as a deilnition oi thelimits of the invention, ref- `output of the generator.

I3 and I l are fed through rectifying buffer ampliilers I5 and I6 tooutput'terminals I1 and I8 of the generator. As will appear more fullyhereinaiter, means are provided in pulser circuits I3 and Il for varyingthe time between generation of pulses at each of the circuits, uponsimultaneous application of saw-tooth wave cycles thereto, to thus varythe time interval or the separation between the double pulse output atterminals I1 and I8. Buier amplifiers II and, I2 function to segregatepulser circuits I3 and I4 from 4the saw-tooth Wave generator IIl andfrom each other so that the outputs of the pulser circuits arecompletely independent of the time interval or separation between thedouble. pulses, while rectifylng buiier ampliiiers I5 and I6 function torectify and amplify the pulsating output of puiser circuits I3 and I4 toproduce extremely sharp pulses of a predetermined polarity at the,

In practically all instances of application of the double pulsegenerator described above, it is A necessary to know the time intervalor the separation between the double pulses. Means are thereforeprovided by the present invention for indicating the output of vthedouble pulse generator and for properly calibrating such indicationascenso Y. 3 I so that the time interval between double pulses may beaccurately measured. As shown in Fig. l. the output of the double pulsegenerator is fed to vertical de'ection plates I9 and of csail-'-lograph. 2 l, while the sweep voltage-for the Oscil- .lograph is.derived directly from the output of sawtooth wave generator i0, andsuch voltase is applied to horizontal deflection plates 23 and 24 of theoscillograph. This `arrangement obtains automatic equality of theoscillograph sweep and the double pulse frequencies as well as maintain#ing extreme steadiness of the oscillograph pattern.V In order tocalibrate the osciiiograph pattern so that the time interval betweendouble pulses 'produced thereon may be readily measured, a calibratedtiming wave is impressed on the vertical deflection plates of theoscillograph. As shown, a timing wave generator io. such as .acalibrated beat frequency oscillator, is provided which supplies altiming wave to the vertical de- :dection plates of the .osciilograph tosuperimpose a timing wave on the oscillograph pattern. In order tomaintain the timing wave pattern on the oscillograph stationary withrespect to the double pulse pattern, the timing wave output of generator80 controls operation of the saw-tooth wave generator i0 to thuscompletely synchronize the entire system.

The circuit diagram' of the double pulse generator isdisclosed in Fig.2. Asshown, saw, tooth wave generator l0 comprises a relaxationoscillator which includes a thermionic gas-filled tube '25 having theplate and cathode thereof re spectively connectedY to positive andgroundpotential in a conventional manner. Capacitances 21, 28 and 29, ofdifferent capacities, may be individually connected in the plate-cathodecircuit of tube 215 in .order to vary the frequency of gen erator i0.Capacitances 30 and 3l are connected to the plate1` of -tube 25, betweenresistentes 32 and 33, for coupling the output of saw-tooth wavegenerator i0 to tubes 34 and 35. When positive potentials appliedthrough resistances l2 and 33, capacitance 29, or capacitance 21 or 2l.receives an increasing charge. the value of which is determined by thevalue of the potential applied to the plate of tube 25, and by the valueof the capacitance. As the charge of either capacitance 21. 28 or 29builds up. the plate of tube 25 receives a corresponding potential. Whenthe .potential on the plate of tub'e 25 reaches a sumcient value torender the tube conducting, the potential charge'of capacitance 21. 28or 29 is discharged through tube 25 to complete generation of thesaw-tooth wave form.

and, as thecharge decreases the Potential of the plate of tube 25likewise decreases. As the plate potential decreases to the cut-oi!potentiel-0f tube 25. the charge on capacitances 21. 2l ori!! againincreases to generating the next saw-tooth wave form. When timing wavegenerator Il is utilized, the potential of the grid of tube 25, which isnormally biased negative through resistance 28, is varied in accordancewith the output ol generator 80 to control the time of discharge of tube25.

The saw-tooth voltage output of generator Il is fed to buifer amplinersI I and I2 each of which respectively include duplex triode vacuum tubes34 and- I5 thus providing a two-stage amplifier. The saw-tooth waveforms are thus amplified and applied tov control grids Il and $1 ofpulser tubes 38 and J9 respectively.' Tubes 38 and .$5 are thermionicgas-filled tubes and are connected in puiser circuits I3 and il in sucha mannerlto cut-off potentials are established at each of the tubes. andthe tubes are therefore rendered conducting when a potential is appliedto the' grids thereof that corresponds to the above mentioned cut-oil'potentials. By applying the necessary negative direct-current potentialto grids Il and 31 to cause the saw-tooth voltages from amplifiers iiand i2, to swing across the cut-oil' potentials of each of the tubes.the tubes will be blocked and rendered conducting upon application ofeach cycle of the saw-tooth voltage. This may be more readily understoodwith reference to Fig. 3, wherein the input voltages to grid Il are-diagrammatically shown; As disclosed, the cuto potential of tube I! isestablished by the positive potential applied to the plate thereof',while the negative direct-current bias on grid Il is saw-tooth voltageto swing across the line representing `the cut-oil potential. When the sawtooth wave sweeps, thus driving grid It more negative, the saw-toothwaveform will cross the line of cut-off potential at point a thusquenching tube It. As the saw-tooth wavecontinues to sweep, the tubewill remain non-conducting until the saw-tooth waveagain crosses theline of cut-ci! potential at point b. Tube 88 then remains in aconductingstate for the completion of the cycle of the sawtooth wave anduntil the subsequent saw-tooth wavecycie passes the line oi' cut-onpotential at Va' to thus again quench the tube. It is to be expresslyunderstood, therefore, that for application of each cycle of thesaw-tooth voltage. tube Il is quenched and then rendered conducting, andtherefore the tube generates a positive and a negative pulse uponapplication of each cycle of the saw-tooth voltage. Since it is desiredto obtain output pulses of minimum width. the pulses generated duringthe time that the tube 38 is rendered conducting are utilized. since ithas been found that the quenching period of the tube is substantiallygreater than the striking time thereof.

As mentioned heretofore. one of the objects of the present. invention isto provide a double pulse generator including means for Avai-.ving thetime interval or the separation between the double pulse. Such meanscomprises'potenticmeters 'I2 and ll which are adapted to control thenegative direct current bias on grids' 3l and I1 in such a manner that.upon simultaneous* application .of a cycle of saw-tooth voltage theretothe tubes will be quenched and rendered conducting at diiferentinstances during movement of the saw-tooth wave cycle to thus generatenegative pulses at different instances. As shown in Fig. 3, since thesaw-tooth voltages vary with respect to the line. of cutoif potentialupon variation of the negative saw-tooth voltages applied to grid 31 arethus caused to cross the line of cut-off potential at higher points onthe saw-tooth waves than the line of cut-oil potential is crossed by thesawtooth waves shown in Fig. 3. Therefore, the tubes are quenched atapproximately the same time since the wave-form of each saw-tooth cycleis substantially vertical when the current is moving more negative, andtube 38 is rendered conducting prior to tube 39 since the line ofcut-off potential of tube 38 is crossed by the saw-tooth wave during theperiod when the latter is becoming less negative, before a similaraction occurs at tube 38. The foregoing means thus prov vides a veryaccurate method of varying the time interval or the separation betweenthe double pulse output of the generator.

Buier amplifiers Il and I2 not only Provide suitable amplification andthe proper number of phase shifts of the saw-tooth voltage output ofgenerator I0, but, as stated heretofore, completely isolate tubes 38 and39 from generator I0 and from each other to prevent interaction betweenthe tubes. When potentiometers 42 and 43 are adjusted in such a mannerthat the separation between the pulse outputs of the tubes is extremelysmall, a few microseconds for example, the grid current drawn by onetube upon generation of a pulse would immediatelyl drive the other tubeconducting, thus reducing the time interval to uro in the event bufferamplifiers II and I2 were not provided.

As stated heretofore, when tubes 38 and 38 are rendered conducting, anegative pulse is generated at the outputs thereof'and such pulses areutilized for the output pulses of the generator.

When the tubes are rendered conducting negative pulses are generatedinstantaneously, followed by a substantially slower rise to normalpotential and therefore it becomes necessary, In order to obtain sharppulses, to amplify the high frequency components of these pulsesandprovide means for rejecting the low frequency components thereof. Suchmeans are included in rectifying buffer amplifiers I5 and I8 each ofwhich comprise a two-stage amplifier having a high transductance tube ineach stage. Amplifier I5 comprising tubes 44 and 45, while tubes 45 and41 are included in amplifier I8. In order to obtain high frequencyresponse of each of the tubes of the ampliiiers suitableinductances areincluded in the plate circuits of each of the tubes. As shownlinductances 48 and 43 are respectively included in plate circuits oftubes 44 and 45 while inductances 50 and 5I are included in similarcircuits associated with tubes 48 and 41. By utilizing hightransconductance tubes in each stageof amplifiers I5 and I8 thenecessary gain is obtained to provide sharp pulses without`substantially increasing the pulse width. By suitably selecting thevalues of inductances 43, 49, 50 and 8|, and the values of resistances52 associated with each of the inductances, a large range of pulsewidths and amplitudes, within certain-.-limits', may be obtained.Amplifiers I5 and I8 are biased insueh 6 a manner to'only amplify thenegative pulses generated by tubes 38 and 39, and protentiometers 53 and54 are included therein for controlling the amplitude of the pulses. Anegative double pulse output is thus obtained at terminals I1 and I8, asdisclosed in Fig. 5 of the drawings. The separation of time interval Tbetween the pulses may be readily varied by operation of potentiometers42. and 43 in a manner Vnoted heretofore.

When the circuit shown in Fig. 2 is utilized in connection withoscillograph 2l in a manner disclosed in Fig. l, the output of timingwave generator. is fed to output terminal I'I by way of connectioncontrolled by switch 55, thus synconducting, grid current is drawn bythese tubes which in turn distorts the saw-tooth wave form of therelaxation oscillator.. Buffer amplifying tubes 34 and35,.positionei|between the relaxation oscillator and the puiser tubes,prevent such distortion of the output wave form of the relaxa-l tionoscillator and consequently prevent a simultaneous distortion of thepulse pattern of the oscillograph.

There is thus provided by the present invention a novel oscillatorcircuit for generating double pulses which includes/means formaintaining a predetermined time interval or separation between thepulses Moreover, means are provided for varying such time interval sothat an extremely small separation, of'a few microseconds, is maintainedbetween the pulses. or for varying such time interval so that asubstantially greater separation is obtained. The circuit is of suchconstruction that extremely sharp pulses of substantially narrow widthare provided at the output thereof and so that 'the pulses may besupplied to a suitable indicator, such as an oscillograph, whereon apattern of the pulses may be obtained' simultaneously with asynchronizing wave whereby the separation may be accurately measured. Yl

The invention described herein may be manufactured and used by or forthe Government of the United States of-America for governmental,purposes without the payment of any royalties thereon or thereforfyWhatis claimed is: l 1. A circuit for generating double pulsescomprisins a pair of electron discharge devices each having a plate, acathode and a control electrode. meansapplying ,equal positivepotentialsto said plates wherebyequal cut-offpotentiais are .established at each.of said devices, meanssimuitaneously applying saw-'tooth voltages toeach of said control electrodes, and means applying direct currentpotentials to each of said control electrodes to cause the saw-toothvoltages to swing across said cut-oil.' potentials wherebyeach of saiddevices is rendered conducting vand quenched upon application rif-.eachcycle ofssaid saw-tooth voltages. i'

v2. A circuit for generating doublefpuises .cor- 'prisinga pair ofelectron discharge devices each. j

havinga platea cathode and a, control electrode' means applying equalpositive potentials to said plates whereby equal cut-oil.'V potentialsare established at each of said devices, means simultaneously applyingsaw-tooth voltages to each of said control electrodes and means applyingdirect current potentials to each of said control electrodes to causethe saw-tooth voltages to swing across said cut-ofi potentials wherebyeach of said devices is rendered conducting and 'selfquenched uponapplication of each cycle of said saw-tooth voltages, the direct currentpotential to one of said electrodes being less than the direct currentpotential to the other electrode i'or rendering one of said devicesconducting before the other device.

3. A circuit for generating double pulses comprising a pair of electrondischarge devices each having a plate, a cathode and a controlelectrode, means applying equal positive potentials to said plateswhereby equal cut-oil' potentials are established at each of saiddevices, means simultaneously applying saw-tooth voltages to each ofsaid control electrodes, means applying direct current potentials toeach of said control electrodes to cause the saw-tooth voltages to swingacross said cut-oil potentials whereby each of said devices is renderedconducting and selfquenched upon application of each cycle of saidsaw-tooth voltages, and means producing a variation in the directcurrent potential to said control electrodes for rendering one of saiddevices conducting before the other device.

4. A double pulse generator comprising a pair of electron dischargedevices each having a plate, a cathode and at least one controlelectrode, means applying equal positive potential to each of saidplates for establishing equal cutfoil potentials at each of saiddevices, means simultaneously applying saw-tooth voltages to each ofsaid control electrodes, means applying direct current potential to eachof said control electrodes for causing the saw-tooth voltages to swingacross said cut-oi! potentials whereby each of said devices is cut-oi!`and rendered conducting and quenched upon application of each cycle oi'said saw-tooth voltages, and means varying the direct current potentialapplied to said control electrodes for varying `the time that the saiddevices are rendered conducting.

5. A double pulse generator comprising a pair of electron dischargedevices each having a plate, a cathode and a control electrode, meansapplying equal positive potential to said plates for establishing equalcut-oi! potentials at each of said devices, means simultaneouslyapplying saw-tooth voltages to each of. said control electrodes in thesame phase relation, means applying negative potential to each of saidcontrol electrodes for causing said saw-toot`h voltages to swing acrosssaid cut-oi! potentials whereby each of said devices is renderedconducting and quenched upon application of each cycle of said saw-toothvoltages, and means .varying the negative potentials applied to said.control electrodes with respect to each other for causing the saw-toothvoltages to cross said cut-oi! potentials at dinerent points where bythe devices are rendered' conducting at different instances.

6. A double pulse generator comprising a oscillator for generatingsaw-tooth wave forms, a pair of non-oscillatingl electron dischargedevices each having a plate, a cathode and a control electrode,

ously applying said saw-tooth wave forms to the control electrodes for'controlling said devices, and means applying negative bias to saidcontrol electrodes for causing said saw-tooth wave forms to swing acrosssaid cut-o potentials whereby each of said devices are quenched and thenrendered conducting upon application of every cycle of said saw-toothwave forms.

7. A double pulse generator comprising a oscillator for generatingsaw-tooth wave forms, a pair of non-oscillating electron dischargedevices each having a plate, a cathode and a control electrode, meansapplying equal positive potentials to each of said plates forestablishing equal cutoff potentials at each of said devices, meanssimultaneously applying said saw-tooth wave forms to the controlelectrodes for controlling said devices, meansl applying negative biasto said control electrodes for causing said saw-tooth'wave forms toswing across said cut-off potentials whereby each oi said devices arequenched and then rendered conducting upon application of' every cycleof said saw-tooth wave forms, and means varying the negative biasapplied to said control electrode for causing the devices to be renderedconducting at different times.

8. A double pulse generator comprising a relaxation oscillatorforgenerating saw-tooth wave forms, a pair of non-oscillating electrondischarge devices each having a plate, a cathode and a controlelectrode, means applying equal positive potentials to each of saidplates for establishing equal cut-ofi potentials at each of saiddevices. means simultaneously applying said saw-tooth wave forms to thecontrol electrodes for controlling said devices, means isolating each ofsaid devices from the other, means applying negative bias to saidcontrol electrodes for causing said saw-tooth wave forms to swing acrosssaid cutoif potentials whereby each of saiddevices are quenched and thenrendered conducting upon application of every cycle of said saw-toothwave forms, and means varying the negative bias applied to saidcontrolelectrode for causing the devices to be 'rendered conducting atdiilerent times. A

9. A double pulse generator comprising a relaxation oscillator forgenerating saw-tooth wave forms, a pair of non-oscillating electrondischarge devices each having a plate, a cathode and a controlelectrode, means applying equal positive potentials to each of saidplates for establishing equal cut-off potentials at each o! saiddevices, means simultaneously applying'said saw-tooth wave forms to thecontrol electrodes for controlling said devices, means applying negativebias to said controlelectrodes for causing said saw-tooth wave forms toswing across said cut-oi! potentials whereby each o! said devices arequenched and then rendered conducting upon application of every cycle ofsaid sawtooth wave forms, means varying the negative bias applied tosaid control electrode for causing the devices to be rendered conductingat different times, and a pair of buner ampliiier means positionedbetween said oscillator and each 'of said devices for preventingYinteraction between the devices.

10. A double pulse generator comprising a relaxation oscillator forgenerating saw-tooth wave forms, a pair of electron dischargef'deviceseach having a plate, a cathode and a control electrode, means applyingequal positive potential to each of said plates for establishing equalcut-oil potentials at each of said devices, means simulphase, meansapplying negative bias to each of said control electrodes for causing'said saw-tooth wave forms to swing across said cut-off potentialswhereby each of said devices is quenched and rendered conducting uponapplication of every cycle of said saw-tooth wave forms to generate apositive and a negative impulse at the output of each of said devices,means varying the negative bias to each of said control electrodes forcausing the devices to be rendered conducting at diilerent instants, andmeans rectifying the output of each of said devices to obtain impulsesof a predetermined polarity.

11. A double pulse generator comprising a relaxation oscillator forgenerating saw-tooth wave forms, a pair of electron discharge deviceseach having a plate, a cathode and a control electrode, means applyingequal positive potential to each of said plates for establishing equalcut-oil potentials at each of said devices, means simultaneouslyapplying said saw-tooth wave forms to each of said control electrodes inthe same phase. means positioned between said oscillator and each ofsaid devices for preventing interaction between the devices, meansapplying negative bias to each of said control electrodes for causingsaid sawtooth wave forms to swing across said cut-off potentials wherebyeach of said devices is quenched and rendered conducting uponapplication of every cycle of said saw-tooth wave forms to generate apositive and a negative impulse at the output of each of said devices,means varying the negative bias to each of said control electrodes forcausing the devices to be rendered conducting at dill'erent instants,and means rectii'ying the output of each of said devices to obtainimpulses of a predetermined polarity.

12. In an apparatus of the class described. an oscillograph, a saw-toothwave generator, means driven by-said generator for producing doublepulses upon application of a unidirectional portion of said saw-toothwave thereto, means applying the double pulses to a pair of deilectionplates of said oscillograph, and means applying the output of saidgenerator to another pair of deflection plates of said oscillograph.

13. In an apparatus of the class, described an oscillograph, arelaxation oscillator for generate' ing saw-tooth waves, a timing wavegenerator for controlling said oscillator, means driven by saidsaw-tooth waves for generating double pulses upon application of aunidirectional portion o f said saw-tooth waves thereto. means applyingsaid double pulses to a pair of deiiection plates of said oscillograph,means applying the output o! said oscillator to another pair ofdeflection plates of said oscillograph, and means passing the output o!said-generator to said one pair of deection plates.

14. In an apparatus of the class described, an oscillograph, a saw-toothwave generator, means driven by said generator for producing doublepulses upon application of every cycle of said sawtooth waves thereto,means varying the time interval between said double pulses, meansapplying the double pulses to a pair of deection plates of saidoscillograph for producing said double 10 pulses on the screen of saidoscillograph where by said time interval may be readily determined.

15. An apparatus of the class described comprising an oscillograph, arelaxation oscillator 5 for generating saw-tooth voltage, a timing wavegenerator controlling said oscillator, means driven by said oscillatorfor generatingI double pulses upon application of every cycle of saidsaw-tooth voltage thereto, means establishing a time interval betweensaid double pulses, means applying said double pulses to one pair ofdeflection plates of said oscillograph, means applying the output.

of said oscillator to another fpair of deflection plates of saidoscillograph for producing a pat-- tern of the double pulses on thescreen of the.

for generating saw toothrvoltages, a timing wavegenerator controllingsaid oscillator, means driven upon application of every cycle of saidsaw tooth voltage thereto, means establishing a time interval betweensaid double pulses, means varying said time interval, means applyingsaid double so pulses to one pair of deilectionplates of saidoscillograph, means applying'the output of said oscillator to anotherpair of deflection plates oifsald oscillograph for producing a doublepulse pattern on the screen of the oscillograph, and means applying theoutput of said generator to said one -pair of deflection plates forsynchronizing the doublepulse pattern onrthe screen of said oscillographwith said timing wave whereby said time interval may vbe accuratelymeasured.

prising a pair of electron 'discharge devices each having a plate, acathode and a control electrode, means applying denite positive poten-`tials to said plates whereby deilnite cut-oil' potentials areestablished at each of said devices, means simultaneously' applyingsaw-tooth voltages to each of said Vcontrol electrodes to cause thesaw-- tooth voltages to swing across said cut-o1 potentials whereby eachof said devices is rendered oonnesting and quenched upon application ofeach cycle of said saw-tooth voltages.

18. A circuit for generating double pulses comprising a pair of electrondischarge devices each having a plate electrode. a cathode and a con-'-trol electrode, means applying positive potentials to said plates, meansapplying direct current negative bias potentials to said controlelectrodes to render the said devices self-quenching, means.simultaneously applying a saw-tooth voltage to A e0 both said controlelectrodes whereby each o! said devices is rendered conducting andquenched f upon application of each cycle offsaid saw-tooth voltage, andmeans varying 'one of the 4said potentials as applied to one of saiddevicesto vary the amount of change in control-.electrode potential bysaid saw-tooth voltage necessary to render the said one deviceconducting.

by said oscillator for generating double pulses 17. A circuit forgenerating'double pulses com-

